Because the type system gives you correctness properties, and gives fast feedback to the coding agent. Much faster to type check the code than let say write and run unit tests.

One possible disadvantage of static types is that it can make the code more verbose, but agents really don't care, quite the opposite.

Funnily enough, when programming with agents in statically typed languages I always find myself in need of reminding the agent to check for type errors from the LSP. Seems like it's something they're not so fond of.